336 Ions produced by fi and 7 Radiations from Radium. 



Further, since the process of ionization by 7 rays is sup- 

 posed to be indirect, the bulk of the energy of the 7 rays- 

 being transferred to the secondary /5 rays, which themselves 

 produce the ionization, it is reasonable also to suppose that 

 the total ionization produced by the primary /9 rays is an 

 approximate measure of their total energy. 



The energy of the different types of rays calculated on this 

 assumption is given in Table II. 



Table II. 





N. 



Heating 



effect gr. cal. 



per hour. 



Average energy 

 emitted 

 per atom. 



.y radiation from EaC 



y radiation from EaB 

 (3 radiation from EaC 

 (3 radiation from EaB ... 



M34xl0 15 1 

 •084xl0 1 5j 

 •64 xlO 15 

 •325 Xl0 15 



5-96 

 6-4 obs. 

 •44 



3'35 calc. 



1*71 calc. 



1-94x10-6 ergs. 

 0-14x10-6 

 1-09x10-6 

 •55x10-6 



Total (3 and y radiation 

 from EaC 



1-774 xlO 15 



9-3 calc. 



302x10-6 





Total (3 and y radiation 

 from EaB 



•41 XlO 15 



2*15 calc. 



•70X10- 6 





Now according to Butherford*, a primary ft particle is 

 expelled from the nucleus of the radioactive atom with a 

 definite initial velocity, but loses a variable part of its energy 

 by exciting the characteristic types of radiation while passing- 

 through the electronic system. The fact that each atom of 

 radium B or radium C emits on the average rather more 

 than one /3 particle t indicates that sometimes the energy 

 converted into 7 radiation is transferred back to a secondary 

 /3 particle before leaving the parent atom. In any case, the 

 combined energy of the /3 and 7 radiations should represent 

 the energy with which the original ft particle would have 

 escaped had it not excited the 7 radiation. The average 

 energy per atom is given in the last column of Table II., 

 and the combined energy per atom for radium C, namely, 

 3*02 x 10 ~ 6 erg, should on this theory be not less than that 

 carried by the fastest of the /3 particles actually observed.. 



* Eutherford, Phil. Mag. xxiv. pp. 453, 893 (1912). 

 t Moseley, loc. cit. 



